Hi, I was developing for Android first and am now doing iOS. I do think that Android is a bigger challenge than iOS, primarily because you have to cater to many different screen sizes. Sure, you have the iPhone 5 which is taller than the other iPhones, but it's more about "clipping" the content for the smaller ones rather than "scaling" the UI up or down for a screen size and Android OS version. It's also heaven how you can have arrays and dictionaries (maps in Java) that contain different data types in Objective-C, even blocks of executable code!
I used to do just Java and knew no C or C++. Below are the references that best helped me to understand the programming philosophy of Objective-C (it's easy to learn the syntax, but why code is being written a certain way is different).
Are you trying to learn Objective-C alone or learn Objective-C and also how to build an iOS app? I know Apple has a ton of resources (videos, documentation, sample code) for almost everything you can do on iOS.
I used to do just Java and knew no C or C++. Below are the references that best helped me to understand the programming philosophy of Objective-C (it's easy to learn the syntax, but why code is being written a certain way is different).
Programming in Objective-C (5th Edition) by Stephen Kochan http://www.amazon.com/books/dp/032188728X
CS193P: Developing Apps for iPhone and iPad (Stanford, via iTunes U) https://itunes.apple.com/us/course/coding-together-developin...